This invention relates to apparatus for processing municipal waste, and more particularly to vibrating mesh screen conveyor systems for removing grit, glass and other noncombustible materials from dry municipal waste.
Municipal waste must be properly processed and disposed of so that it does not create health risks to the community. Generally, municipal waste, which may be collected in garbage trucks, dumpsters or the like, is deposited in processing areas such as landfills. Land and environmental controls imposed on landfill operators by governmental bodies have increased in recent years, however, making land fill disposal of solid waste materials more expensive.
Municipal waste materials typically include noncombustible materials such as glass, metal and grit, and combustible materials such as paper. Disposal of the combustible materials by burning them eases the burden on landfill operators in complying with certain governmental regulations. In addition, increases in the cost of fossil fuels has enhanced the value of such combustible materials, because such materials may have up to half the heating value of coal, and can be substituted for or cofired with coal or other fossile fuels such as oil and natural gas.
Combustible waste materials, called refuse derived fuel, may be produced from municipal waste by mechanically separating combustible materials from glass, grit, metal and other noncombustibles. Generally, particle size is reduced first by using shear shredders. Ferrous material is removed with magnetic separators, and trommels or disk screens separate combustible pieces from noncombustible pieces. However, trommels and disk screens, with related apparatus, are relatively expensive. Thus, there is a need for relatively inexpensive and efficient methods and apparatus for separating combustible from noncombustible materials in solid municipal waste.
Vibrating screen conveyors have been used for sorting vegetables and for separating litter from rocks along roadsides. However, such conveyors could become clogged if they were used to separate combustible from noncombustible waste materials because municipal waste typically includes wires, strips of various materials such as nylons, and other objects which can easily become caught in the screen. Thus, there is also a need for vibrating screen conveyors which separate combustible from noncombustible materials in municipal waste, without becoming clogged.
Accordingly, one object of this invention is to provide new and improved apparatus for processing municipal waste materials.
Another object is to provide new and improved vibrating screen conveyor systems for processing municipal waste materials.
Still another object is to provide new and improved vibrating screen conveyor systems for removing grit, glass and other noncombustible matter from solid municipal waste materials.